Cardiopulmonary interventions to decrease blood loss and blood transfusion requirements for liver resection
Abstract
Background
Blood loss during liver resection is one of the most important factors affecting the peri‐operative outcomes of patients undergoing liver resection.
Objectives
To determine the benefits and harms of cardiopulmonary interventions to decrease blood loss and to decrease allogeneic blood transfusion requirements in patients undergoing liver resections.
Search methods
We searched The Cochrane Hepato‐Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until November 2008 for identifying the randomised trials.
Selection criteria
We included all randomised clinical trials comparing various cardiopulmonary interventions aimed at decreasing blood loss and allogeneic blood transfusion requirements in liver resection. Trials were included irrespective of whether they included major or minor liver resections, normal or cirrhotic livers, vascular occlusion was used or not, and irrespective of the reason for liver resection.
Data collection and analysis
Two authors independently identified trials for inclusion and independently extracted data. We analysed the data with both the fixed‐effect and the random‐effects models using RevMan Analysis. For each outcome we calculated the risk ratio (RR), mean difference (MD), or standardised mean difference (SMD) with 95% confidence intervals (CI) based on intention‐to‐treat analysis or available case‐analysis. For dichotomous outcomes with only one trial included under the outcome, we performed the Fisher's exact test.
Main results
Nine trials involving 587 patients satisfied the inclusion criteria. The interventions included low central venous pressure (CVP), autologous blood donation, haemodilution, haemodilution with controlled hypotension, and hypoventilation. Only one or two trials were included under most comparisons. All trials had a high risk of bias. There was no significant difference in the peri‐operative mortality or other peri‐operative morbidity. None of the trials reported long‐term survival or liver failure.The risk ratio of requiring allogeneic blood transfusion was significantly lower in the haemodilution and haemodilution with controlled hypotension groups than the respective control groups. Other interventions did not show significant decreases of allogeneic transfusion requirements.
Authors' conclusions
None of the interventions seem to decrease peri‐operative morbidity or offer any long‐term survival benefit. Haemodilution shows promise in the reduction of blood transfusion requirements in liver resection surgery. However, there is a high risk of type I (erroneously concluding that an intervention is beneficial when it is actually not beneficial) and type II errors (erroneously concluding that an intervention is not beneficial when it is actually beneficial) because of the few trials included, the small sample size in each trial, and the high risk of bias. Further randomised clinical trials with low risk of bias and random errors assessing clinically important outcomes such as peri‐operative mortality are necessary to assess any cardiopulmonary interventions aimed at decreasing blood loss and blood transfusion requirements in liver resections. Trials need to be designed to assess the effect of a combination of different interventions in liver resections.
PICOs
Plain language summary
Haemodilution may show promise in decreasing blood loss and blood transfusion requirements
Blood loss during liver resection (partial removal of liver) is one of the important factors affecting the post‐operative complications of patients. Allogeneic blood transfusion (using blood donated by a different individual) is associated with increased morbidity and lower survival in patients with liver cancer. This systematic review was aimed at determining whether any cardiopulmonary (interventions that change the circulation or breathing during surgery) intervention decreased blood loss or decreased allogeneic blood transfusion requirements in patients undergoing liver resections. This review included nine trials with 587 patients. All trials had high risk of bias ('systematic error') as well of play of chance ('random error'). The interventions included low central venous pressure (CVP; pressure in the major neck veins), autologous blood donation (using the patient's own blood obtained prior to liver resection), haemodilution (replacing blood with other fluids), haemodilution with controlled hypotension (lowering the blood pressure in addition to diluting the blood), and hypoventilation (decrease the rate of artificial breathing), and were compared with controls not receiving the interventions. There was no difference in the death or complications due to surgery in any of the comparisons. Long‐term survival was not reported in any of the trials. Fewer patients required transfusion of blood donated by others when haemodilution or haemodilution with controlled hypotension were compared to controls. The other comparisons did not decrease the transfusion requirements. However, there is a high risk of type I errors (erroneously concluding that an intervention is beneficial when it is actually not beneficial) and type II errors (erroneously concluding that an intervention is not beneficial when it is actually beneficial) because of the few trials included and the small sample size in each trial as well as the inherent risk of bias (systematic errors). Haemodilution shows promise in the reduction of blood transfusion requirements in liver resections. Further randomised clinical trials with low risk of bias (systematic errors) and low risk of play of chance (random errors) which assess clinically important outcomes (such as death and complications due to operation) are necessary to assess any cardiopulmonary interventions aimed at decreasing blood loss in liver resections. Trials need to be designed to assess the effect of a combination of different interventions in liver resections.
